Impact of Pretreatment Technologies on Saccharification and Isopentenol Fermentation of Mixed Lignocellulosic Feedstocks
- 920 Downloads
In order to enable the large-scale production of biofuels or chemicals from lignocellulosic biomass, a consistent and affordable year-round supply of lignocellulosic feedstocks is essential. Feedstock blending and/or densification offers one promising solution to overcome current challenges on biomass supply, i.e., low energy and bulk densities and significant compositional variations. Therefore, it is imperative to develop conversion technologies that can process mixed pelleted biomass feedstocks with minimal negative impact in terms of overall performance of the relevant biorefinery unit operations: pretreatment, fermentable sugar production, and fuel titers. We processed the mixture of four feedstocks—corn stover, switchgrass, lodgepole pine, and eucalyptus (1:1:1:1 on dry weight basis)—in flour and pellet form using ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate, dilute sulfuric acid (DA), and soaking in aqueous ammonia (SAA) pretreatments. Commercial enzyme mixtures, including cellulases and hemicellulases, were then applied to these pretreated feedstocks at low to moderate enzyme loadings to determine hydrolysis efficiency. Results show significant variations on the chemical composition, crystallinity, and enzymatic digestibility of the pretreated feedstocks across the different pretreatment technologies studied. The advanced biofuel isopentenol was produced during simultaneous saccharification and fermentation (SSF) of pretreated feedstocks using an engineered Escherichia coli strain. Results show that IL pretreatment liberates the most sugar during enzymatic saccharification, and in turn led to the highest isopentenol titer as compared to DA and SAA pretreatments. This study provides insights on developing biorefinery technologies that produce advanced biofuels based on mixed feedstock streams.
KeywordsMixed feedstock Biomass pellet Biomass pretreatment Isopentenol Simultaneous saccharification and fermentation Ionic liquid Dilute acid Soaking aqueous ammonia
This work conducted by the Joint BioEnergy Institute was supported by the Office of Science, Office of Biological and Environmental Research, of the US Department of Energy under Contract No. DE-AC02-05CH11231. ABPDU acknowledges the funding support from Office of Biomass Program within the US DOE’s Office of Energy Efficiency and Renewable Energy, and also the funding support from the American Recovery and Reinvestment Act. We acknowledge Vicki S. Thompson and Neal A. Yancey from Idaho National Laboratory for providing biomass feedstocks and Sonny Zhang for lab assistance. We thank Novozymes for the gift of the enzyme mixtures used in this study.
Conflict of Interest
The authors claim no competing interests.
JS, KG, and NS conducted pretreatment, saccharification, and fermentation experiments. JS and KG conducted data analysis and drafted the manuscript. WH and CL carried out the calorimetric measurements while VS performed pXRD. SS, TSL, JDK, and BAS coordinated and supervised the research and collaborative efforts. All authors read and approved the final manuscript.
- 2.Milbrandt A (2005) A geographic perspective on the current biomass resource availability in the United States. Technical Report: NREL/TP-560-39181Google Scholar
- 5.Theerarattananoon K, Xu F, Wilson J, Staggenborg S, Mckinney L, Vadlani P, Pei Z, Wang D (2012) Effects of the pelleting conditions on chemical composition and sugar yield of corn stover, big bluestem, wheat straw, and sorghum stalk pellets. Bioprocess Biosyst Eng 35(4):615–623CrossRefPubMedGoogle Scholar
- 7.Pirraglia A, Gonzalez R, Saloni D (2010) Techno-Economical Analysis of Wood Pellets Production for Us Manufacturers. Bioresources 5(4):2374–2390Google Scholar
- 8.Jacobson JJ, Carnohan S, Ford A, Beall A (2014) Simulating Pelletization Strategies to Reduce the Biomass Supply Risk at America’s Biorefineries. Paper presented at the 2014 International System Dynamics ConferenceGoogle Scholar
- 11.Stelte W, Sanadi AR, Shang L, Holm JK, Ahrenfeldt J, Henriksen UB (2012) Recent Developments in Biomass Pelletization - a Review. Bioresources 7(3):4451–4490Google Scholar
- 17.ASTM (2012) Standard test method for sampling granular carriers and granular pesticides. vol ASTM E725-96. doi: 10.1520/E0725-96R12
- 18.Selig M, Weiss N, Ji Y (2008) Enzymatic Saccharification of Lignocellulosic Biomass.Technical Report: NREL/TP-510-42629; Golden, CO, 2008Google Scholar
- 23.DOE (2012) 2011 Platform Review Report An Independent Evaluation of Platform Activities for FY 2010 and FY 2011. Washington DCGoogle Scholar
- 24.Wyman CE, Balan V, Dale BE, Elander RT, Falls M, Hames B, Holtzapple MT, Ladisch MR, Lee YY, Mosier N, Pallapolu VR, Shi J, Thomas SR, Warner RE (2011) Comparative data on effects of leading pretreatments and enzyme loadings and formulations on sugar yields from different switchgrass sources. Bioresour Technol 102(24):11052–11062. doi: 10.1016/j.biortech.2011.06.069 CrossRefPubMedGoogle Scholar
- 29.Park S, Baker JO, Himmel ME, Parilla PA, Johnson DK (2010) Cellulose crystallinity index: measurement techniques and their impact on interpreting cellulase performance. Biotechnology for Biofuels 3. doi: 10.1186/1754-6834-3-10
- 33.Li CL, Knierim B, Manisseri C, Arora R, Scheller HV, Auer M, Vogel KP, Simmons BA, Singh S (2010) Comparison of dilute acid and ionic liquid pretreatment of switchgrass: Biomass recalcitrance, delignification and enzymatic saccharification. Bioresour Technol 101(13):4900–4906. doi: 10.1016/j.biortech.2009.10.066 CrossRefPubMedGoogle Scholar
- 35.Shi J, Ebrik MA, Yang B, Garlock RJ, Balan V, Dale BE, Pallapolu VR, Lee YY, Kim Y, Mosier NS, Ladisch MR, Holtzapple MT, Falls M, Sierra-Ramirez R, Donohoe BS, Vinzant TB, Elander RT, Hames B, Thomas S, Warner RE, Wyman CE (2011) Application of cellulase and hemicellulase to pure xylan, pure cellulose, and switchgrass solids from leading pretreatments. Bioresour Technol 102(24):11080–11088. doi: 10.1016/j.biortech.2011.04.003 CrossRefPubMedGoogle Scholar
- 36.Wyman CE, Dale BE, Balan V, Elander RT, Holtzapple MT, Ramirez RS, Ladisch MR, Mosier NS, Lee YY, Gupta R, Thomas SR, Hames BR, R. W, R. K (2013) Comparative Performance of Leading Pretreatment Technologies for Biological Conversion of Corn Stover, Poplar Wood, and Switchgrass to Sugars. In: Wyman CE (ed). doi: 10.1002/9780470975831
- 37.Olofsson K, Bertilsson M, Lidén G (2008) A short review on SSF-an interesting process option for ethanol production from lignocellulosic feedstocks. Biotechnol Biofuels 1(7):1–14Google Scholar